Notes, summaries, assignments, exams, and problems for Biology

Organisation and Composition of Life

Levels of Organisation

Abiotic (Non-living) Levels

• Atom Level
• Molecule Level
• Macromolecule Level

Biotic (Living) Levels

• Organelle Level: e.g., Mitochondria
• Cellular Level: The fundamental unit of life
• Multicellular Level:
  • Tissue Sublevel
  • Organ Sublevel
  • Organ System Sublevel

Composition of Matter

• Primary Bioelements: Carbon, Hydrogen, Oxygen, Nitrogen, Sulfur, Phosphorus (CHONSP)
• Secondary Bioelements: e.g., Calcium, Sodium
• Trace Bioelements: e.g., Iron, Zinc

The Building Blocks of Life

Cell Characteristics

Structure and Functions

• Cell Membrane: Surrounds, protects, and regulates the transfer of substances.
• Cytoplasm with Organelles: Carries out vital cellular functions.
• Genetic Material: Contains the instructions for life.

Cell

Deoxyribonucleic acid, or DNA, is a molecule that contains the instructions an organism needs to develop, live, and reproduce. These instructions are found inside every cell and are passed down from parents to their children.

Structure of DNA

DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group, and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G), and cytosine (C). The order of these bases is what determines DNA's instructions, or genetic code. Human DNA has around 3 billion bases, and more than 99 percent of those bases are the same in all people, according to the U.S. National Library of Medicine (NLM).

Similar to the way the order of letters in... Continue reading "DNA Structure, Transcription, and Translation Explained" »

Organs and Organ Systems

Organs

Organs are complex structures composed of various types of tissue. They perform single or similar functions.

Organ Transplant

Organ transplant is the replacement of a damaged organ or tissue. A common problem is rejection.

Organ Systems

• Nutrition:
  • Digestive system: Digests food and absorbs nutrients.
  • Respiratory system: Exchanges O2 and CO2.
  • Circulatory system: Transports substances throughout the body.
  • Excretory system: Removes metabolic waste, such as urine.
• Interaction:
  • Nervous system: Receives stimuli and sends instructions.
  • Endocrine system: Produces hormones.
  • Locomotive system: Enables movement and provides protection.
• Reproduction:
  • Reproductive system: Creates new life.

Health and Illness

Concept of Health

Health is a state... Continue reading "Human Body: Organs, Systems, Health, and Disease" »

Phospholipid molecules form a bilayer - phospholipids are fluid and move laterally

Peripheral proteins are bound to either the inner or outer surface of the membrane

Integral proteins - permeate the surface of the membrane

The membrane is a fluid mosaic of phospholipids and proteins

Proteins can move laterally along membrane

Diffusion is the movement of particles from a region of high concentration to a region of low concentration, and is the result of the random motion of particles.

Facilitated diffusion is similar to simple diffusion, except that it requires channel proteins or carrier proteins, which are specific to the molecules being transported across the plasma membrane from high concentration to low concentration.

Osmosis is the passive movement... Continue reading "Cell Membrane Structure and Function" »

Fibra:Fiber is a complex carbohydrate of plant origin. Humans
cannot digest fiber or use it as a source of energy or
matter, but it is nonetheless essential for the functioning
of the digestive system.

Nutrients:Organic nutrients: are complex molecules produced by

Inorganic nutrients: are simple molecules that can be
found in living organisms, but have not been produced by
them. These nutrients are essential to your body but do
not supply any energy.
○ Minerals (such as calcium and sodium)
○ Water
○ Oxygen

Vitamins:Vitamins are organic components that the body either
cannot produce or produces only in insufficient
quantities.
● These must be obtained from food.
● All vitamins are needed in small quantities and they are
essential for regulating many... Continue reading "Where is cellobiose found in living organisms" »

Homeostasis and Environmental Response

All living things interact with their environment, including their surroundings and other organisms.

The environment is constantly changing. To survive and reproduce, living organisms must detect these changes and respond appropriately.

Responding to Stimuli

1. A stimulus is detected by receptors (structures or organs).
2. The stimulus is relayed to coordination systems, which interpret the signal and produce a response.
3. The organism responds using effectors (organs or structures).

Maintaining Internal Balance

To survive, living organisms must regulate their internal conditions.

Examples of internal conditions include temperature, water content, and concentrations of mineral salts and glucose in the blood.

Changes in... Continue reading "Homeostasis and Stimuli in Living Organisms" »

Heart Anatomy and Function

Chambers and Valves

The heart is a muscular, hollow organ divided into four chambers:

• Upper Chambers (Atria): Left atrium and right atrium.
• Lower Chambers (Ventricles): Left ventricle and right ventricle.

Between the atrium and ventricle, the atrioventricular valve allows blood flow from the atrium to the ventricle but prevents backflow. The valve between the left atrium and ventricle is bicuspid, while the valve between the right atrium and ventricle is tricuspid.

Blood Circulation

Cardiac Cycle

• Atrial Systole: Atria contract, pumping blood into the ventricles through open atrioventricular valves.
• Ventricular Systole: Ventricles contract, sigmoid valves open, and blood flows into the pulmonary artery and aorta. Atrioventricular

NO BANK/FIB-MULTI Panceras

Endocrine Functions § Pancreatic islets § Secrete hormones insulin and glucagon into blood Exocrine functions § Secretes pancreatic juice into duodenum § Alkaline fluid introduced with enzymes neutralizes chyme from stomach Pancreatic Juice

• Water, bicarbonate solution, enzymes
• Bicarbonate solution: neutralizes gastric HCL & shift pH of duodenum to 8
• Enzymes: § Pancreatic amylase: digests salts § Trypsinogen - digests proteins § Lipase - digests triglycerides

Agriculture:

Deliberate land modification through plant cultivation and raising animals for food or profit Dominant economic activity Requires physical and demographic contributions in regions

Hemoglobin:

Globin combined with 4 iron atoms • 280 million molecules... Continue reading "Endocrine Functions of the Pancreas and Other Organ Systems" »

Menstrual Cycle

Pre-menstrual phase: the lining of the uterus begins to break down, progesterone decreases. Menstruation: the endometrium is detached, loss of blood and it is caused by progesterone. Usually it lasts 4 days. Repair phase: the lining of the uterus starts to thicken and becomes more stable. Increase in the concentration of estrogen. Ovulation: occurs around day 14, the ovum is released, there is a peak of estrogen and they are the most fertilized days. Receptive phase: the lining of the uterus is well developed if the ovum has been fertilized it implants itself in the tissue. Hormones: FSH: stimulates the follicle (brain) LH: produces ovulation (brain). Estrogen: creates new endometrium (ovary). Progesterone: makes the endometrium... Continue reading "Understanding the Menstrual Cycle, Pregnancy, and Reproduction" »

Organs Involved in Excretion

Excretion is the process by which the waste products from cell metabolism are eliminated from the blood.

Kidneys

Kidneys eliminate toxic substances resulting from cell metabolism through the urine.

Lungs

Lungs expel carbon dioxide from cellular respiration.

Liver

Liver produces a liquid called bile that helps to eliminate waste from digestion through feces.

Sweat Glands

Sweat glands, exocrine glands of the skin, are responsible for sweat excretion. Sweat is a liquid that is very similar to urine, but more diluted.

Nephrons and the Formation of Urine

Nephrons are the basic functional units of the kidneys. Each kidney has about one million. Urine is a liquid made of water, salts, and waste. This is done using filtration and... Continue reading "Organs Involved in Excretion and the Formation of Urine" »